A typical one of the track frame assemblies of this type for use in the conveyor systems is disclosed in the Japanese Patent No. 3498179 of the Applicant of the present invention, for example.
The track frame assembly is to be used with conveyor chains or the like used in the conveyor system. It includes a pair of metallic frame members and an appropriate number of coupling clamps which couple the pair of frame members together parallel and opposite to each other.
Each of the frame members is a generally elongated channel-like structure including an elongated base plate portion and elongated bent plate portions formed contiguous to the lateral sides (longer sides), respectively, of the base plate portion. The elongated base plate portion has a concavity formed to extend longitudinally. The concavity is formed to have a generally “dove-tail” cross section which is defined by a pair of elongated slant walls extending to the position of the bent plate portion and gradually more divergent as it goes toward the end of the longer side and an elongated back wall connecting the ends of the longer sides of the slant walls in pair to each other.
The elongated bent plate portion has formed at the end of the longer side thereof an elongated folded-back portion extending toward the base plate portion. Each of the coupling clamps includes a pair of clamps and a fastener capable of connecting the clamps toward each other. The concavity in each frame member is grasped at the back thereof by an engaging portion provided at either end of the clamps in pair.
However, the track frame assembly of the above-mentioned type is disadvantageous in that a time longer than expected is required for a high-precision assembling because the track frame assembly includes the pair of metallic frame members and appropriate number of clamps for coupling the pair of frame members to each other.
Also, the synthetic resin-made track rail is disadvantageous in that it is compatible with only a conveyor chain corresponding in shape to the frame member because it is installed to cover a part of the bent plate portion of the frame member and the folded-back portion.
That is, to make the conventional track frame assembly compatible with various types of conveyor chains, not only the track rail but the frame members have to be modified in shape and dimensions, which will disadvantageously add to the costs of the conveyor system using the track frame assembly. Also, since the track rail is installed to cover the folded-back portion, the engaging projection of the conveyor chain possibly slides in direct contact with a metallic guide and scatters abrasion-caused metal powder.
Furthermore, when the track rail and frame members are installed, it is difficult to assure ample strength of the installation. When the track rail is applied with a large external force, longitudinal misalignment will possibly be caused, resulting in lateral backlash.